Conventionally, there is provided an IVR (interventional radiology)-CT (Computed Tomography) apparatus obtained by combining an X-ray CT apparatus and an X-ray diagnostic apparatus. The IVR-CT apparatus has, for example, a function of supporting an operation such as puncture. In this case, the IVR-CT apparatus can generate MPR (Multi-Planar Reconstruction) images including an axial image, sagittal image, coronal image based on a point designated on a generated projection image.
That is, the conventional IVR-CT apparatus can display three types of MPR images. An axial image is generated according to, for example, an axial slice calculated based on a preset temporary height and a position designated on a projection image, as shown in FIGS. 20, 21, and 22. At this time, the axial image includes a point of interest assumed based on the preset temporary height and the position designated on the projection image. However, the assumed point of interest may deviate from a point of interest desired by an operator. Consequently, the conventional IVR-CT apparatus cannot display the point of interest desired by the operator.
The IVR-CT apparatus determines a position to which a CT gantry is to be desirably moved, as follows. First, a point (to be referred to as an input point hereinafter) desired by the operator is input on the projection image. A temporary point of interest (to be referred to as an assumed point hereinafter) is determined based on the preset temporary height and the input point. The moving position of the CT gantry is determined based on the coordinate of the assumed point in the long-axis direction of a top plate (FIG. 20). In the above method, for example, as shown in FIG. 20, a position at a predetermined height from the upper surface of the top plate is set as a point desired by the operator. Therefore, as shown in FIGS. 21 and 22, when the distance (to be referred to as the height of the point of interest hereinafter) between the top plate and the position of the point of interest desired by the operator is different from the temporary height, the CT gantry moving position corresponding to the point of interest desired by the operator unwantedly deviates from that determined by the above method.
Consequently, when the position designated on the projection image deviates from a line segment which passes through the center position of an X-ray detector and is parallel to the short-axis direction of the top plate, the CT gantry moving position deviates from the position desired by the operator. That is, the determination accuracy of the CT gantry moving position degrades.
Furthermore, to accurately determine the CT gantry moving position, for example, X-ray imaging may be executed for an object a plurality of times. In this case, the radiation exposure dose of the object undesirably increases.